#include<iostream>
using namespace std;
const static double PI = 3.14159;

class Point {
    private:
        double x,y;
    public:
        Point(double a,double b):x(a),y(b) {}
        double area() {return 0;}
};

class Circle : public Point {
    private:
        double radius;
    public:
        Circle(double a,double b,double r):Point(a,b),radius(r) {}
        double area() {
            return PI * radius * radius;
        }
};

int main() {
    Circle c(1,2,3);
    Point * pc = &c;
    Point &rc = c;
    cout << "c.area() = " << c.area() << endl;
    cout << "pc->area() = " << pc->area() << endl;
    cout << "rc.area() = " << rc.area() << endl;
    return 0;
}
